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參數資料
| 型號： | AD9226AST |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | ADC |
| 英文描述： | Complete 12-Bit, 65 MSPS ADC Converter |
| 中文描述： | 1-CH 12-BIT FLASH METHOD ADC, PARALLEL ACCESS, PQFP48 |
| 封裝： | PLASTIC, LQFP-48 |
| 文件頁數： | 16/28頁 |
| 文件大小： | 1480K |
| 代理商： | AD9226AST |
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REV. 0
AD9226
–16–
V
IN
A
CAPB
1V p-p
49
49
AD9226
AD8138
1k
0.1 F
4.7 F
1k
49
499
15pF
499
499
0.1 F
10 F
0.1 F
CAPT
0.1 F
450
V
IN
B
Figure 6a. Direct-Coupled Drive Circuit with AD8138
Differential Op Amp
0
–
20
–
40
–
60
–
80
–
100
–
120
0
4
8
12
16
MHz
20
24
28
32
SNR = 66.9dBc
SFDR = 70.0dBc
d
Figure 6b. FS = 65 MSPS, f
IN
= 30 MHz, Input Span = 1 V p-p
The same midsupply potential may be obtained from the
CMLEVEL pin of the AD9226 in the LQFP package.
Referring to Figure 7, a series resistor, R
S
, is inserted between the
AD9226 and the secondary of the transformer. The value of
33 ohm was selected to specifically optimize both the THD and
SNR performance of the ADC. R
S
and the internal capacitance
help provide a low-pass filter to block high-frequency noise.
Transformers with other turns ratios may also be selected to
optimize the performance of a given application. For example, a
given input signal source or amplifier may realize an improve-
ment in distortion performance at reduced output power levels
and signal swings. By selecting a transformer with a higher
impedance ratio (e.g., Minicircuits T16-6T with a 1:16 imped-
ance ratio), the signal level is effectively
“
stepped up
”
thus
further reducing the driving requirements of signal source.
VINA
VINB
AD9226
49.9
R
S
33
MINICIRCUITS
T1-1T
0.1 F
R
S
33
0.1 F
10 F
0.1 F
0.1 F
CAPB
CAPT
15pF
1k
1k
AVDD
Figure 7. Transformer-Coupled Input
SINGLE-ENDED DRIVER CIRCUITS
The AD9226 can be configured for single-ended operation using
dc- or ac-coupling. In either case, the input of the ADC must be
driven from an operational amplifier that will not degrade the
ADC
’
s performance. Because the ADC operates from a single
supply, it will be necessary to level-shift ground-based bipolar
signals to comply with its input requirements. Both dc- and
ac-coupling provide this necessary function, but each method
results in different interface issues which may influence the
system design and performance.
Single-ended operation requires that VINA be ac- or dc-coupled
to the input signal source, while VINB of the AD9226 be biased
to the appropriate voltage corresponding to the middle of the input
span. The single-ended specifications for the AD9226 are char-
acterized using Figure 9a circuitry with input spans of 1 V and
2 V. The common-mode level is 2.5 V.
If the analog inputs exceed the supply limits, internal parasitic
diodes will turn on. This will result in transient currents within
the device. Figure 8 shows a simple means of clamping an input.
It uses a series resistor and two diodes. An optional capacitor is
shown for ac-coupled applications. A larger series resistor can
be used to limit the fault current through D1 and D2. This
can cause a degradation in overall performance. A similar
clamping circuit can also be used for each input if a differen-
tial input signal is being applied. A better method to ensure
the input is not overdriven is to use amplifiers powered by a single
5 V supply such as the AD8138.
AVDD
AD9226
R
S1
30
V
CC
V
EE
OPTIONAL
AC-COUPLING
CAPACITOR
D2
D1
R
S2
20
Figure 8. Simple Clamping Circuit
AC-COUPLING AND INTERFACE ISSUES
For applications where ac-coupling is appropriate, the op amp
output can be easily level-shifted by means of a coupling
capacitor. This has the advantage of allowing the op amp
’
s com-
mon-mode level to be symmetrically biased to its midsupply
level (i.e., (AVDD/2). Op amps that operate symmetrically with
respect to their power supplies typically provide the best ac
performance as well as greatest input/output span. Various high-
speed performance amplifiers that are restricted to +5 V/
–
5 V
operation and/or specified for 5 V single-supply operation can be
easily configured for the 2 V or 1 V input span of the AD9226.
Simple AC Interface
Figure 9a shows a typical example of an ac-coupled, single-
ended configuration of the SSOP package. The bias voltage
shifts the bipolar, ground-referenced input signal to approxi-
mately AVDD/2. The capacitors, C1 and C2, are 0.1
μ
F ceramic
and 10
μ
F tantalum capacitors in parallel to achieve a low
cutoff frequency while maintaining a low impedance over a
wide frequency range. The combination of the capacitor and the
resistor form a high-pass network with a high-pass
–
3 dB fre-
quency determined by the equation,
f
–
3
dB
= 1/(2
×
π
×
R
×
(C1 + C2))
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相關代理商/技術參數 |
參數描述 |
|---|---|
| AD9226ASTRL | 功能描述:IC ADC 12BIT 65MSPS 48-LQFP RoHS:否 類別:集成電路 (IC) >> 數據采集 - 模數轉換器 系列:- 產品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:2,500 系列:- 位數:12 采樣率（每秒）:3M 數據接口:- 轉換器數目:- 功率耗散（最大）:- 電壓電源:- 工作溫度:- 安裝類型:表面貼裝 封裝/外殼:SOT-23-6 供應商設備封裝:SOT-23-6 包裝:帶卷 (TR) 輸入數目和類型:- |
| AD9226ASTZ | 功能描述:IC ADC 12BIT 65MSPS 48-LQFP RoHS:是 類別:集成電路 (IC) >> 數據采集 - 模數轉換器 系列:- 標準包裝:1 系列:microPOWER™ 位數:8 采樣率（每秒）:1M 數據接口:串行，SPI? 轉換器數目:1 功率耗散（最大）:- 電壓電源:模擬和數字 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:24-VFQFN 裸露焊盤 供應商設備封裝:24-VQFN 裸露焊盤（4x4） 包裝:Digi-Reel® 輸入數目和類型:8 個單端，單極 產品目錄頁面:892 (CN2011-ZH PDF) 其它名稱:296-25851-6 |
| AD9226ASTZRL | 功能描述:IC ADC 12BIT 65MSPS 48LQFP RoHS:是 類別:集成電路 (IC) >> 數據采集 - 模數轉換器 系列:- 標準包裝:1 系列:- 位數:14 采樣率（每秒）:83k 數據接口:串行，并聯 轉換器數目:1 功率耗散（最大）:95mW 電壓電源:雙 ± 工作溫度:0°C ~ 70°C 安裝類型:通孔 封裝/外殼:28-DIP（0.600"，15.24mm） 供應商設備封裝:28-PDIP 包裝:管件 輸入數目和類型:1 個單端，雙極 |
| AD9226-EB | 制造商:Analog Devices 功能描述:EVAL BD FOR AD9226 ADC CNVRTR - Bulk |
| AD9226-LQFP-EB | 制造商:AD 制造商全稱:Analog Devices 功能描述:Complete 12-Bit, 65 MSPS ADC Converter |
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